"Master Yi's slated for a visual upgrade and kit rework in a coming
patch. In addition to a new model, more polished animations and expanded
voice over, each of Yi's abilities are getting updates to address
issues with his popular AP and AD builds. His kit should still feel
familiar to both AP and AD enthusiasts, and we're hoping to retain most
of the fun aspects of both playstyles.

We had three basic goals with the Master Yi updates:

Polish up Master Yi's art and aesthetics so they hit the same level of polish as new champions

Merge the most enjoyable aspects of AP and AD Yi into a single cohesive playstyle

Place more emphasis on mastering Yi's abilities so he's less frustrating in lower level play and scales better with player skill

Why'd Master Yi get a new look?
Master Yi was one of the first League of Legends champions ever created.
Back then the game had a less established artistic identity. We've
learned a lot over the years, but we also thought it was important to
preserve his core look and feel as a part of LoL history. The
differences are subtle, but when you check out the new Yi you'll notice
his proportions are more in line with his fellow champs, his animations
are more polished and he has some sweet new acrobatic moves on Alpha
Strike, Double Strike and Highlander.

Why does Yi need a design update?
Most of AD Yi's power comes from his basic attack combined with the
steroid effects on Wuju Style, Highlander and Double Strike. Without AP,
there's almost no incentive to master your active skills – Meditate's
not a very effective disengage and Alpha Strike can actually make you
lose DPS since you could be attacking during the cast animation. By
contrast, AP Yi requires careful management of Alpha Strike, Meditate
and Wuju Style to maximize damage and survivability, but doesn't do a
whole lot with his basic attack until he gets Lich Bane.
While both these playstyles are interesting in their own right, they
don't necessarily have to be mutually exclusive, and there's probably a
unified design that offers the best of both. Moreover, while AP Yi's a
rather compelling late game fighter, he's extremely frustrating to face
in lane, so scaling back Alpha Strike and Meditate was a necessary part
of the update.

What's happening to AP Yi?
While straight AP probably won't remain a prominent build, AP Yi players
will find many of the familiar elements of their playstyle intact.
While Alpha Strike and Meditate are scaled back so they're less
overwhelming in lane, carefully managing your active abilities will play
an important role in staying alive and maximizing your DPS. You'll also
have the added power of AD Yi's basic attack to make up for your less
devastating Alpha Strikes.

How's the new Master Yi play?
We imagine the updated Master Yi will work well in both mid lane and the
jungle. We definitely want to skew his itemization away from the
typical tank-heavy fighter builds. The updated kit rewards glass cannon
DPS builds that rely on disengaging with Alpha Strike and Meditate to
stay alive. Most of his power still comes though items rather than
natural scaling through levels. Overall, Master Yi players should have
more strategic options, and more incentive to master his full kit to
fight effectively."

"I can answer a couple things about the kit in the... 15 or so minutes
I have here - sorry there isn't much. Solcrushed, who is handling a
lot of the tight-end balance will be around in the afternoon, I think.

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Playstyle and Kit

Overall, none of his targetting paradigms have changed - nor have any of the abilities changed in their use case.

The majority of this was scaling, timing, cleanup and a couple minor retouches.

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Alpha Strike

For example, Alpha Strike now scales off total Attack Damage,
deals physical damage and has some light interactions with critical
strike and attack speed.

Hitting an enemy will reduce the cooldown of Alpha Strike - while
critical strike will add mini-crits to the skill based on your critical
strike chance and damage.

Alpha Strike will have fixed travel time between bounces - so an Alpha
Strike on 4 targets will give you a consistent time of untargetability,
rather than being proximity based. This also means that your opponents
will have a better sense of when you'll fade back in, so good luck on
that.

Alpha Strike has lost its AP ratio... for now. We're experimenting with
some models here under-the-hood for a pure AP playstyle - unsure how
it'll fully pan out.
Alpha Strike now counts as movement for the purposes of items such as Statik Shiv.

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Meditate

Meditate has changed from a flat armor / magic resistance boost to
a % DR model as penetration was causing really weird damage potentials
against what is supposed to be one of Yi's primary defense mechanisms.

It also restores more health the lower health you have - meditating at
lower health will provide a bigger damage buffer / health restore in
general than meditating at high health.

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Wuju Style

Wuju Style has been changed from a flat boost to a % boost in
total attack damage. This smooths out his power curve a bit better based
on how well he's doing throughout the game, rather than spiking early
at around level 9 and then really needing to snowball off a couple kills
to remain decent.

Wuju's style's active now deals true damage based on a % of his total
attack damage - Master Yi needs to be a threat, regardless of who he's
attacking - but the damage difference between destroying squishy targets
and piercing high armor targets was getting a bit absurd.

In general, Wuju Style will add less attack damage early but more and
more as he builds additional Attack Damage and ranking it. We've
compensated some of this early damage loss with an increase in base
statistics and survivability.

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Highlander

One of the things we noticed from continuous playtests was that
the more you made Yi focus on Alpha Strike and Highlander gameplay - the
more of a restriction Highlander became.

One of the primary skills a player needs to know while playing Yi is
when to engage a fight - but seeing so many opportunities pass by
because you were waiting for an apparently unrelated cooldown
(Highlander) seemed counter-intuitive for the build.

Highlander now has a passive/active component - the passive restoring
basic cooldowns on kills and assists - while the active keeps the speed
benefits that the original highlander had. Note, however, that
Highlander will not reset itself passively or actively.

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Double Strike

Double Strike was operating in a burst paradigm that seemed
anti-thesis to the continuous threat pattern that we wanted to build up -
Especially with Alpha Strike becoming a larger part of threat for AD -
this spiked his assassin pattern to an unhealthy level.

Double Strike has been retuned as a building-up paradigm. Every 4th
attack, Master Yi's next attack will strike twice for 100% damage and
50% on the second hit - but he must use this additional double strike
within the next couple of seconds - This also had some neat synergies
with the retuned Alpha Strike and Wuju Style."

"We have elements on our champions that are very iconic, and very dear to that champion in general. Karma's fans is a very strong example of this that we learned from.

For Master Yi, we saw no reason to remove them. They add a tiny bit of visual clutter, but for the most part, we would be making the champion more generic by removing them. They add to his fantasy, they add to his silhouette, and they add to the thought that this dude has so many swords that he's truly a master of his own style.

Additionally, did you know that the swordboots/bootswords/shoedaggers only appear on Base and Assassin? We kept this the same."